Water volume calculator
Pick a shape, enter its dimensions in meters, centimeters, feet or inches and a fill level. You get the volume of water in liters, US gallons and cubic meters.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Pick the shape closest to what you are measuring.
- Choose the unit and enter the dimensions. Use the average water depth for ponds.
- Optionally lower the fill level if the container is not full.
- Read the volume in liters, US gallons and cubic meters.
| Shape |
Volume |
| Rectangle |
length x width x depth |
| Round |
pi/4 x diameter2 x depth |
| Oval |
pi/4 x length x width x depth |
| Sloping floor |
length x width x (shallow depth + deep depth) / 2 |
Dimensions are converted to meters with exact factors (1 cm = 0.01 m, 1 in = 0.0254 m, 1 ft = 0.3048 m). 1 m3 = 1,000 L, and 1 US gallon = 3.785411784 L.
Worked example
A pool 5 m long, 3 m wide and 1.5 m deep holds 5 x 3 x 1.5 = 22.5 m3, which is 22,500 liters or about 5,944 US gallons. A round barrel with a 1 m diameter and 1 m of water holds pi/4 = 0.785 m3, or 785 liters.
Tips
- Measure the water depth, not the wall height; most containers are not filled to the rim.
- For a pool with a deep end and a shallow end, use the sloping floor shape.
- For irregular shapes, split them into rectangles and circles, calculate each and add the results.
Frequently asked questions
How is the volume of each shape worked out?
A rectangle is length x width x depth. A round tank is pi/4 x diameter squared x depth. An oval is an ellipse, pi/4 x length x width x depth. A sloping floor uses the average of the shallow and deep depth, which is exact when the floor slopes evenly.
How many liters are in a cubic meter?
One cubic meter is exactly 1,000 liters. One US gallon is exactly 3.785411784 liters, so one cubic meter is about 264.17 US gallons.
Are the results exact for a real pond?
Only for the ideal shapes. Natural ponds have uneven edges and floors, so use an average depth and treat the result as an estimate, usually a little high for rounded corners.
Why use the fill level?
Water is rarely filled to the very top. Enter the percentage of the full volume you actually fill, for example 80 percent of a barrel or a pool filled below the rim.
Is this for imperial gallons?
No, the gallon shown is the US gallon. One imperial gallon is 4.54609 liters, so divide the liters by 4.54609 for imperial gallons.